1. Field of The Invention
The present invention relates to an apparatus for screeding. A wooden or metal manual screed board, which is notched on both ends, rides on rails, which are placed in U-channels. The invention includes hollow topped supporting pipes, which are located at a desired height above the grade. Grade pins are then inserted into the hollow tops of each pipe. The pipes and the grade pins are then hammered downward until the top of the grade pin is at the desired finished proper elevation. The grade pins are then removed and the U-channels are then dropped into the pre-located pipes. Because of the dimensions of all components, the rails are supported a desired height above grade so that using the screed board on the rails produces a surface with not only the required smoothing and depth, but also one of the required slope. The heights of the U-channels can be adjusted using pipe spacers.
2. Description of the Related Art
Screeds of various configurations are known in the prior art.
Chambers, U.S. Pat. No. 413,846, discloses a road grader with an elongated board 10, which is manually pulled on trucks riding on rails.
Thorson, U.S. Pat. No. 1,832,951, shows a machine for troweling concrete paving.
Tamblyn, U.S. Pat. No. 2,306,671, discloses a screed, which rides in rails supported by C-channels mounted in pipe holders. The rails or runways 16 are best shown in FIGS. 5-7. At page 2, right hand column, lines 8-11, it is the level of the runways 16 which determine the level of the screed.
Kubula, U.S. Pat. No. 3,182,572 is a concrete belting machine. The device rides on rails, which are embedded in the ground.
Samprey, et al., U.S. Pat. No. 4,289,421 show a road screed incorporating an auger and a vibrator.
Morrison, U.S. Pat. No. 4,386,901, and Morrison, U.S. Pat. No. 4,701,071 disclose motorized two screeds which do not require guide rails.
U.S. Pat. No. 6,223,495, Shaw, et al. issued May 1, 2001, FIG. 3, shows a screed post assembly having a C shaped support for a rail 28. The C shaped support has a number of apertures 52 for changing the position of the rail 28 in the support.
Holmes U.S. Pat. No. 5,924,818 issued Jul. 20, 1999 teaches that changing the slope in a screed and a structure for accomplishing such a change.
Other patents are U.S. Pat. Nos. 6,273,636; 6,238,134; 6,056,474; 5,980,154; and U.S. Pat. No. 5,567,075.
These prior art devices are generally characterized by mechanical complexity in structure and in design.
The apparatus of the present invention is used, for example, in the installation of interlocking concrete pavers. Installation of such pavers involves the requirement to excavate the site to depths dependent on the type of underlying soil and the purposes for which the pavers are to be used. One commercial manufacturer recommends excavation of 7xe2x80x3-8xe2x80x3 in sandy soil for sidewalks/patios and 11xe2x80x3-12xe2x80x3 on clay. The depths are increased to 11xe2x80x3-12xe2x80x3 on sandy soil for driveways and 15xe2x80x3-16xe2x80x3 on clay. Slope and grade have to be established. The same manufacturer recommends a 1xe2x80x3 elevation drop for every 34 feet for drainage. Slope for specific locations is usually determined by qualified engineers. Layers of sub-base material and sand are located in the excavated site. The sub-base material is compacted to a level within 3xe2x80x3 from the finished height. The finished sub-base material must reflect the final grade. Sand is placed on the sub-base material. Both the sub-base material and the sand are smoothed by a screed. All of the dimensions of the installation are laid out with a transit or a sight level elevator, stakes and string.
The present invention eliminates the need for stakes and string to establish elevation. The installation is laid out with hollow ended pointed rods. The rods have markings on them to indicate the proper height for patio/walkway and driveway. Grade pins or jackhammer pins are inserted into the hollow ends of each rod to vertically position the rods to the proper markings. The pins are then replaced with U shaped rail supports. Rails are then inserted between supports. A screed board notched to ride on each rail is then used to smooth the surface of the sub-base material and the sand layer. Spacers in the form of hollow cylinders of a range of lengths are provided to adjust the height of the U shaped support, as required. For example, if the industry standard requires a 1xe2x80x3 sand layer over the sub-base, use of a 1xe2x80x3 spacer will produce the required 1xe2x80x3 sand layer.
A principal object and advantage of the invention is the provision of a method and apparatus for manual screeding.
Another object and advantage of the invention is the provision of a supporting base for mechanical as well as manual screed devices.
Another object and advantage of the invention is the provision of a screed, which also eliminates the need for use of string and stake to provide proper elevations.
A still further object of the invention is the provision of a screed, which includes grade or jackhammer pins, which located in hollow support rods so that the height of the resultant screed is within required tolerances.
Another object and advantage of the invention is the provision of a screed where grade or jackhammer pins are also used to prevent damage to the hollow support rods when the rods are hammered into place.
Another object and advantage of the invention is the provision of screed, which provides a plurality of different fine height adjustments by using different length hollow cylinders placed beneath the screed board supports.
A still further object and advantage of the invention is the provision of a screed system, which is inexpensive and easy to use.